Currently, there are many writing instruments, for example, retractable ball-point pens, known in the art that have built-in lamps, such as LED lamps, thus making the pen usable in a dark environment. Usually, retractable pens with built-in lamps work as follows: when a pen's writing end is extended out of the pen, the built-in lamp turns on, and when the pen's writing end is retracted, the lamp turns off. However, pens of the above kind have a serious shortcoming: the lamp always turns on when the pen's writing end is out, which reduces a lamp battery life as the lamp stays turned on even in a bright environment when the lamp is not needed for writing.
There are retractable lamp pens known in the art that have separate switches for turning a built-in pen lamp on and off. However, the above solution also has a shortcoming in that it requires providing additional hardware associated with a lamp switch, which results in increased cost, assembly problems, and diminished reliability compared to a conventional retractable pen. Furthermore, a user has to use two separate switches in one pen, one for extending a pen's writing end out of the pen's body, and another for illuminating the lamp. Therefore, there is a need to provide a retractable pen having a built-in lamp that would switch on only when necessary, for example, in a dark environment, and that could be turned off in a light environment, wherein extending and retracting the writing end of the pen and turning on and off the built-in lamp can be operated by a single switch.